A mask for use during painting shields those components of the contents of a wall box which will be exposed through a decorative plate used to cover the wall box after the wall is painted. The mask is a substantially flat thin sheet with an adhesive substance applied to its face along its outer perimeter for adhering the sheet to the wall. The substance may be continuous or may be spotted about the perimeter. A pad of identical masks can be temporarily held in stacked laminar relationship by the adhesive substance. The mask may also have a raised portion of perimeter, depth and location suitable for shielding any of the contents of the box which protrude from the box beyond the plane of wall surface. The raised portions may be tapered to facilitate nesting of identical masks in a pad temporarily held in stacked laminar relationship by the adhesive substance.